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Lesser Knots (Calidris canutus) are high-Arctic breeding waders that migrate to temperate and tropical regions for the non-breeding season. Seasonal mass changes were examined in Lesser Knots in New Zealand at the southern end of their migration. Adults showed a large increase in mass in February before their northward migration in March. They were estimated to depart with a ‘fat’ load of around 45%. Subadult birds, most of which winter in New Zealand over the northern breeding season, also showed a mass increase. Mass increases in winter are well documented for European waders but contrary to the European situation, this increase in subadult birds in New Zealand is unlikely to be an adaptive strategy to insure against periods of negative energy balance. Instead, it may be an endogenously orchestrated byproduct that has not been selected against in the pre-migratory period. Such increases may be more widespread in Arctic waders in the Southern Hemisphere than is realised.

Sections of nine rivers in the Upper Waitaki Basin were surveyed between 1991 and 1994 and these surveys were compared with counts completed in 1962, 1965 and 1968. A systematic account of 27 wetland birds is given. Densities (number of birds km-1) of birds were compared between the two periods. Species that increased in density were mainly common generalists, whereas species that decreased in density were endemic river breeding specialists. Densities of Wrybills (Anarhynchus frontalis), Spur-wing Plovers (Vanellus miles), Canada Geese (Branta canadensis), and Grey Teal (Anas gracilis) were higher in the 1990s than in the 1960s, whereas densities of Banded Dotterels (Charadrius bicinctus), waterfowl and shags, Black-billed Gulls (Larus bulleri), South Island Pied Oystercatchers (Haematopus ostralegus), Black-backed Gulls (L. dominicanus) and Black-fronted Terns (Sterna albostriata) were lower in at least one river in the 1990s compared to the 1960s. Estimated minimum populations of river birds published for the Ahuriri River (surveyed in 1982) and the Cass River (surveyed in 1979 and 1982) were usually intermediate to those recorded in equivalent 1960s and 1990s surveys. Four mechanisms that explain changes in braided river bird populations are suggested.

Dispersal of colour-banded South Island Pied Oystercatchers Haematopus ostralegus finschi from a breeding area on farmland in mid-Canterbury, New Zealand, was investigated from December 1987 to September 1997. Most moved north and were away from the breeding area from late December to mid-July. All birds spent this time at coastal sites, which ranged from 97 to 834 km from their breeding area. Distances travelled by males and females and birds of all ages were similar. Birds had high fidelity to wintering sites within and between years. Pair bonds were not maintained in winter and there was no evidence that fledglings accompanied their parents to wintering sites.

Between March 1992 and February 1993, 222 five-minute stationary bird counts were conducted at 12 sites in the Kennedy’s Bush Scenic Reserve on Christchurch’s Port Hills. Over the period of the survey, 22 species of bird were recorded in or flying over the reserve. The seven most frequently recorded species were Silvereye (Zosterops lateralis), Grey Warbler (Gerygone igata), Bellbird (Anthornis m. melanura), Fantail (Rhipidura fuliginosa), Chaffinch (Fringilla coelebs), Blackbird (Turdus merula) and Redpoll (Acanthis flammea). Kennedy’s Bush does not contain a high diversity of native bush birds compared to some other mainland sites. Native species also appear less abundant in Kennedy’s Bush than in continuous, climax forest sites near Reefton. Kennedy’s Bush does, however, support high numbers of some species such as Silvereye, Grey Warbler, Fantail, Bellbird and Shining Cuckoo (Chrysococcyx l. lucidus) compared to sites at Kowhai Bush, Kaikoura. The autumn peak in numbers of Silvereye recorded at Kennedy’s Bush may result from flocks of migrating birds, some of which may move out of the reserve for the winter months. The numbers of Grey Warbler, Bellbird and Blackbird recorded probably reflect seasonal changes in conspicuousness rather than a change in actual numbers; adults are probably resident in the reserve year round. As in other parts of Canterbury, Fantail numbers were severely reduced by the heavy snow-falls of August 1992. Bellbird numbers were also reduced by the heavy snow-falls. Spring brought high numbers of Chaffinches to the reserve and summer brought high numbers of Redpolls, both of which were apparently absent or in very low numbers during winter. Small numbers of Goldfinches (Carduelis carduelis) and Greenfinches (Carduelis chloris) also appear to occur in Kennedy’s Bush only during the summer months. Of particular interest were records of two rarer Port Hills birds, Tomtits (Petroica m. macrocephala) and New Zealand Pigeons (Hemiphaga n. novaeseelandiae). Tomtits were recorded on only two occasions over the survey period. By 1997, however, this species appeared to be resident in the reserve. New Zealand Pigeons were recorded in Kennedy’s Bush in small numbers throughout the year and may breed there.

The sediment ponds and tidal flats at Port of Whangarei have been significant roost areas for waders since they were created from dredge tailing in the late 1960s. In 1971, 11 species of waders fed or roosted in this area; New Zealand Dotterel (Charadrius obscurus), White-fronted Tern (Sterna striata), Caspian Tern (S. caspia) and Black-backed Gull (Larus dominicanus) bred there, and on six islands of mud and shell. Intensive observation in 1979-80 and 1995-98 found that the residency status of many species had changed. There were significant declines in the numbers of New Zealand Dotterel, Caspian Tern and Skylark (Alauda arvensis), and significant increases in the numbers of Red- billed Gull (L. novaehollandiae scopulinus) and House Sparrow (Passer domesticus). These changes were associated with development of sedimentation ponds and increases in weed-stabilised communities and cover by mangroves. Future bird use of this area is very dependent on the management of the ponds, and the rate of encroachment of mangroves or ponds over the main mudflat roost area. A new island would safeguard wader roosting in the upper harbour.

Aspects of the ecology of the Antipodes Island Parakeet (Cyanoramphus unicolor) and Reischek’s Parakeet (C. novaezelandiae hochstetteri) were examined at the Antipodes Islands during October and November 1995. Significant differences in diet were detected between the species. Leaves of large tussocks formed the majority of the diet for Antipodes Island Parakeets, whereas tussock flowers comprised much of the diet of Reischek’s Parakeet. Significant differences in the diet of these species between this and previous studies were thought to reflect temporal variations in food availability rather than any fundamental shift in dietary preferences. Observations were made of both parakeet species scavenging on bird corpses. Antipodes Island Parakeets were also recorded killing and eating Grey-backed Storm Petrels (Oceanites nereis). One Antipodes Island Parakeet nest was located; clutch size, physical characteristics of the nest and of behaviour during incubation are described.

A colour-banded sample of New Zealand Snipe (Coenocorypha aucklandica) was studied on the Snares Islands over six breeding seasons. Snipe reached densities of 11.5 birds/ha; they were serially monogamous, but alpha males regained their original partner and territory at the start of the following breeding season. Up to 47% of males and 30% of females were excluded from breeding each year, although they were tolerated within breeding territories. Breeding adults were highly faithful to their territories and mates regardless of previous breeding success. About 83% of adults were seen in the study area the year after banding. No males moved to different territories, and only 11% of females moved, all to adjacent territories. Less than 9% of breeders changed partners between years if their previous mate was still present.Territory area was not influenced by intruder density: in years of high population density a higher proportion of birds was excluded from breeding. Non-breeding adults obtained a territory or mate only if a territorial bird died. Prior residence was an important factor in acquiring a territory both within and between breeding seasons. Mortality was density-dependent, and a relatively constant proportion of non-breeding birds was assimilated into the breeding population each spring.New Zealand Snipe were faithful to their natal area; 46% of fledglings were later seen in the study area. There was no sex bias in return rates, but females tended to disperse slightly further than males. About 11% of males and 57% of females bred as 1-year-olds. Previously non-territorial birds (beta status) gained access to territories and mates when alpha status birds were caring for chicks. No inbreeding was recorded.

Banded Dotterels (Charadrius bicinctus bicinctus) exhibit a variety of seasonal movement patterns ranging from sedentary behaviour, through migration within New Zealand, to trans-Tasman migration. From 1985 to 1990 the Ornithological Society of New Zealand (OSNZ) studied the regional patterns of movement of Banded Dotterels which had been colour-banded on the breeding grounds. Sight-recoveries indicated that most birds in inland regions of the southern half of the South Island migrated to Australia, but coastal breeding birds in the South Island were mostly sedentary. Inland birds north of Canterbury mostly moved within New Zealand, particularly to harbours in the North Island but with regionally specific patterns – Westland birds mainly to Farewell Spit, Marlborough birds to the northern North Island and Farewell Spit, southern North Island birds either locally or to the Auckland region, and most Hawkes Bay and Volcanic Plateau birds to Bay of Plenty and Auckland. Breeding habitat modified this pattern; coastal birds were mainly sedentary, whereas birds on nearby inland riverbeds were migratory. Migration patterns are discussed in terms of advantages and disadvantages of different wintering options.

The nesting activities and breeding success of Black Shags (Phalacrocorax carbo) near Lake Kohangatera, Wellington, were studied from 1993 to 1998. The colony was used during November-July by a mean of 67 birds per night, but in August-October numbers increased to a mean of 98 birds when fledglings were present. Courtship and nest- building began in March, and nesting continued until October-November when the last chicks fledged. Most clutches (85% of 185) were laid in April-May (early nests), the remainder being laid in June-September (late nests). The mean estimated laying date of early nests varied from 14 April in 1998 to 3 May in 1995, the overall mean (1993-98) being 24 April. During the day typically the male took two incubation stints, including the first, and the female one or two. The mean length of incubation stints by females was 3 h 46 min, over an hour longer than that of males. However, the mean time females and males were absent from the colony to forage, 2 h 39 mins and 2 h 21 mins respectively, did not differ significantly. Three types of changeovers seen during incubation are described, as are the activities of adults and chicks during nestling rearing. Fledglings took their first flights when 49-60 days old, but continued to be fed by their parents for 40 to 80 days afterwards, the oldest fledged young seen fed being about 140 days old. Of 185 breeding attempts during 1993-98, 83% were successful, the majority resulting in one or two fledglings per nest. Mean brood size at fledging varied with year, from 1.1 in 1997 to 1.7 in 1998. Overall, the mean brood size was 1.4 fledged young per nest, and 1.7 for successful attempts. Early clutches were more productive than late ones. We conclude that a pair of Black Shags would be unable to successfully rear two broods and complete their moult within a year, and that late nestings were replacement clutches.

I tested the ability of captive Black Stilt chicks (Himantopus novaezelandiae) to capture and consume common aquatic invertebrates. Waterboatmen (Sigara sp.), segmented worms (Oligochaeta), and larvae of a damselfly (Xanthocnemis zealandica), midge (Chironomus zealandicus), mayfly (Deleatidium spp.), and caddisfly (Aoteapsyche colonica) were captured and consumed quickly and easily by chicks of all ages (2 – 30 days). They were also consumed in the greatest numbers. In contrast, two aquatic snails (Physa acuta and Lymnaea tomentosa) and larvae of two cased caddisflies (Triplectides sp. and Hudsonema amabilis) were captured and consumed with difficulty and in low numbers by young chicks (

Waders were counted monthly for six years at the three high tide roosts which are normally used by more than 50% of the waders in the Firth of Thames. The annual cycle of wader numbers is shown for all waders and selected species. The data are used to “correct” wader count data and demonstrate that such “correction” changes apparent population trends. Timing of future bi-annual wader censuses can be improved to maximise counts and/or to minimise variability.